Acid bowl cleaner



a United States Patent Ofifice 3,173,875 Patented Mar. 16, 1965 Michigan No Drawing. Filed Nov. 9, 1961, Ser. No. 152,131

12 Claims. (Cl. 252--105) This invention relates, in general, to acid detergent compositions. More particularly, it pertains to attenuated acid compositions particularly adapted for removing stains from porcelain-type fixtures.

Porcelain fixtures such as those customarily found in lavatories are readily susceptible to iron staining where the water conveyed to and drained from the fixture has an initial high iron content and where the water solubilizes iron in lower valence state from iron conduits leading into the fixtures. The problem of iron staining is particularly acute when, after draining the water, a thin film of water remains on the porcelain fixture. Upon evaporation of this film, iron salts remain which are readily converted to the higher valence state. It is this form of the iron which adheres so tenaciously to the fixture and which is, therefore, responsible for the unsightly and undesirable iron stains.

It has been customary to employ acidic compositions to remove these stains. Thus, cleaning compositions based upon hydrochloric acid or sodium bisulfate are well known in the art. Sodium bisulfate, also known as niter cake, depends for its stain removal action on the formation of sulfuric acid on contact with water. The Federal specification for bowl cleaners issued by the General Services Administration, OC-42 6D, August 19, 1957, is based upon sodium hydrogen sulfate. This specification requires that, upon analysis by titration of a suitable solution, the material must have a sulfuric acid equivalent of not less than 30 weight percent.

Since cleaners containing sodium bisulfate as the active ingredient depend on the release of a strong acid for stain removal properties, there are, therefore, certain precautions and restrictions in their use. This type of cleaning compound should not be employed on metal or enamel fixtures. It should not be allowed to contact the skin and, in addition, inhalation of the cleaner dust should be avoided.

A review of bowl cleaning compositions based upon sodium hydrogen sulfate is set forth in an article by Milton A. Lesser entitled Washroom Sanitation Specialties, Soap and Sanitary Chemicals, page 139, October 1947.

Acidic cleaning compositions based on muriatic acid and particularly adapted for use at institutional-type facilities such as public carrier terminals and industrial plants generally contain about 20 to 23 weight percent of hydrogen chloride. These compositions are, in general, subject to the same precautions and restrictions as previously set forth for sodium bisulfate.

Although acidic cleaning compositions based upon either hydrochloric acid or sodium bisulfate, at the concentrations noted above, are effective for removing stains from porcelain-type fixtures, they are, however, particularly hazardous to handle.

Therefore, it is an object of the invention to provide acid detergent compositions which are relatively safe and easy to handle. Another object of the invention is to provide attenuated acid cleaners for removing stains from porcelain-type fixtures which are as effective as the hazardous-to-handle acid compositions of the prior art. A further object of the invention is to provide a process for removing stains from porcelain-type fixtures wherein the cleaning compositions employed in the process are as effective as the acid compositions of the prior art but are not as hazardous to handle.

In accordance with the invention, it has been discovered that when a sgluble ferrou s salt isaddedtoan acid selected from the group consisting of phosphorig cid, hydrochl o ric a c id and mixttge giereof, it surprisingly and unexpectedly incEases the rate atwhich the acid removes stains from porcelain-type fixtures. Thus, a mild acid such as phosphoric acid when employed in combination with a soluble ferrous salt will remove stains at a faster rate than, for example, a 20 weight percent aqueous solution of hydrochloric acid. In addition, and in accordance with the invention, less concentrated solutions of hydrochloric acid can be employed in combination with a soluble ferrous salt and these attenuated combinations remove stain at a faster rate than the 20 weight percent hydrochloric acid compositions of the prior art.

The prior art discloses that stannous chloride solutions acidulated with tartaric acid can be employed to remove iron oxide and carbonaceous deposits from the interior of glass molds. Thus, US. 2,116,034, McGaughey, discloses that five pounds of stannous chloride and one gallon of water, which water has been acidulated with ounce of tartaric acid, provides a composition for reducing the iron oxide deposits on the interior surface of such molds. McGaughey points out that only enough of the tartaric acid is used to give the water and acidic characteristic and that the tartaric acid is necessary for producing a suitable solvent for the stannous chloride.

The composition disclosed by McGaughey for removing iron oxide deposits from glass molds was evaluated for its capacity to remove iron stains from porcelain fixtures. In addition, a comparative study was made in order to ascertain the effectiveness of certain of the compositions of the invention when employed at the concentration disclosed by McGaughey. The composition of the invention employed was an aqueous solution of phosphoric acid and ferrous chloride. Comparative studies were also carried out at 10 weight percent acid concentration and 2 and 32 weight percent reducing agent concentration, respectively.

The procedure employed for evaluating stain removal properties was somewhat similar to that described in Federal Specification P-P-00586, Revision 1, August 24, 1 955. Briefly, the staining procedure consisted of applying a 5% ferric chloride solution on an unglazed porcelain plate and setting the stain by baking for two hours at C. The plate was cooled and a drop of the stain removal solution to be tested was applied thereto. The rate of stain removal was determined by measuring the time necessary to remove all of the stain in the area covered by the test drop.

The composition, concentration and rate of stain removal are set forth in Table A below. In this table, M represents the composition disclosed by McGaughey and X represents the composition of the invention previously defined. Under the heading A, the compositions are compared on the preferred weight basis set forth in the McGaughey disclosure. Under the headings B and C,

weight percent of the acid has been employed and 2 and 32 weight percent of the reducing agent has been used, respectively. Under the heading D, an aqueous solution of 10 weight percent phosphoric acid was employed as the stain removal agent. In each instance, the quantities are expressed on a weight percent basis.

iected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof.

Although the concentrations described above give good results, it is preferred, however, in order to obtain a better balance of properties to employ an acid detergent composition comprising about 5 to weight percent a 32 weight percent reducing agent concentration, the composition of the invention is more than 100 times as effective as the composition disclosed by McGaughey. In addition, it will be noted from the table that the Me- Gaughey disclosure, at the various concentrations set forth, does not remove stain as fast as an aqueous solution of 10 weight percent phosphoric acid.

The compositions of the invention comprise an aqueous solution of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate, and mixtures thereof in combination with an acid selected from the group consisting of hydrochloric acid, phosphoric acid, and mixtures thereof. The ingredients of the composition can be varied over a wide range and still maintain the advantages of the invention. However, the acid detergent composition of this invention should contain at least about 0.2 weight percent of an acid selected from the group consisting of phosphoric acid, hydrochloric acid and mixtures thereof and at least about 0.5 weight percent of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof. While any amounts of ferrous salt and of acid above the minimums recited are effective and produce the desired results of this invention, it is desirable, due to the cost of the acids and ferrous salts, to use the minimum amount necessary for the particular cleaning job. In this connection, consideration must be given to solubility limitations. In general, amounts of acid in excess of 30 weight percent and amounts of ferrous salt in excess of 38 weight percent are insoluble in the aqueous solution and, thus, such excess amounts do nothing to increase the effectiveness of the solution. Accordingly, it is not desirable to use such excess amounts of acid and ferrous salt although solutions containing such excess amounts are effective. Thus, the acid detergent composition of this invention generally comprises an aqueous solution of about 0.2 to 30 weight percent of an acid selected from the group consisting of phosphoric acid, hydrochloric acid and mixtures thereof and about 0.5 to 38 weight percent of a water-soluble ferrous salt se- Table A A B o M X M X M x Tartarie Acid 0.2 10.0 10.0 Stannous Chloride 37.5 2.0 32.0 Phosphoric Acid 0. 2 10. 0 10. 0 10. 0 Ferrous Chloride 37. 2.0 32. Water 62.3 62.3 88.0 88.0 58.0 58.0 90.0

Stain removal rate, See 1,610 190 2,650 55 680 6 670 $402. 5lbs.

It will be noted from the table that the compositions of phosphoric acid and about 6 to 30 weight percent of of the invention are from about 8 to about times 25 the water-soluble ferrous salt or about 6 to 20 weight more effective for removing iron stains from a porcelain percent hydrochloric acid and about 1 to 24 weight perplate than a similar composition based on the Mccent of the water-soluble ferrous salt.

'Gaughey disclosure. Thus, as illustrated under head- Mixtures of hydrochloric acid and phosphoric acid can ing A, when the compositions are compared on the also be formulated with a soluble ferrous salt in order same weight basis as set forth in the McGaughey 30 to provide an acid cleaning composition of significantly disclosure, the composition of the invention is about 8 improved properties. When a mixture of the acids is times more effective for removing stain. However, as employed, the compositions have the same proportions illustrated under heading C, when the compositions are as set forth above except that up to 75 weight percent compared at a 10 weight percent acid concentration and 35 of the acid can be phosphoric acid.

The soluble ferrous salts which can be employed to accelerate the rate at which the mineral acids remove stain and deposit from porcelain-type fixtures consist of ferrous chloride, ferrous sulfate and ferrous nitrate. Mixtures of these ferrous salts are also suitable i the compositions of the invention. A mixture of soluble ferrous salts is particularly desirable, however, when the compositions of the invention are prepared in stainless steel equipment. Thus, it has been found that when the acid composition is formulated with ferrous chloride alone, the formulated composition has a tendency to corrode the steel equipment used for its preparation. However, when the acid composition is formulated with a mixture of ferrous chloride and ferrous sulfate, the corrosiveness of the composition towards stainless steel is significantly minimized or completely eliminated. A preferred composition for such application is an aqueous solution of about 18 to 22 weight percent of phosphoric acid, about 2 to 6 weight percent of ferrous chloride and about 6 to 10 weight percent of ferrous sulfate. No problem of corrosion is encountered, however, when rubher-lined equipment is employed to prepare the acid compositions of the invention.

A preferred bowl cleaning composition which is particularly adapted for sale in the industrial and domestic market is an aqueous solution of about 5 to 25 Weight percent of phosphoric acid, about 6 to 30 weight percent of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixture thereof, about 10 weight percent of isopropanol and about 0.5 weight percent of an alkyl benzene sodium sulfonate wherein the alkyl group contains from about 10 to 15 carbon atoms.

In order to further illustrate the invention and its accompanying advantages, the following specific examples are presented.

The procedure employed in each of the examples was, unless otherwise stated, to prepare a 5% solution of ferric chloride from anhydrous ferric chloride of A.C.S. grade. The ferric chloride solution was then applied to one side of an unglazed porcelain streak plate and the stain was.

set by baking the plate for two hours at 130 C. The plate was cooled and a drop of the solution being evaluated for stain removal properties was applied thereto. The rate of stain removal was determined by measuring the time necessary to remove all the stain in the area covered by the test drop. In each instance, the concentration is set forth in weight percent.

EXAMPLE I Table I 1101 9 2O 36 I1 0 91 90 8O 64 Destaining time, See 300 345 45 1 EXAMPLE II Ferrous chloride was added to aqueous solutions of hydrochloric acid and drops of the resulting compositions were applied to test plates stained in accordance with the procedure outlined above and the stain removal rates were determined. The concentrations of hydrogen chloride and ferrous chloride in each solution and stain removal rates are set forth in Table II below. It will be noted from the table that ferrous chloride significantly increases the rate at each aqueous solutions of hydrochloric acid remove stain from porcelain surfaces. Of most significance, however, is the discovery that an aqueous solution of 9 weight percent hydrogen chloride and 6.3 weight percent ferrous chloride (10 weight percent FeCl -4H O) is as etfective as a 20 weight percent solution of hydrochloric acid. Thus, a less concentrated acid can be used to achieve results which formerly required a more concentrated form of the acid.

A drop of each solution was ous-to-handle hydrochloric acid of the prior art for removing stains from porcelain surfaces.

Table III H3PO4..- 1 5 10 20 Calculated FeClg 38.0 25.4 25.4 25.4

Destaining time, See 12 90 50 20 EXAMPLE IV Aqueous solutions of ferrous chloride were applied to test plates stained in accordance with the procedure previously outlined in order to determine the effectiveness of ferrous chloride, per se. The concentration of the ferrous chloride solutions and the rate of stain removal are set forth in Table IV below. It will be noted from the table that at the end of one hour the stains had not been removed.

Table IV FeC-h-4H 0 15 30 11:0 85 40 Calculated FeCl 9. 5 19.0 38.0 Destuining time, See... 3, 600 3, 600 3, 600

EXAMPLE V Ferrous chloride, ferrous sulfate, a surfactant and perfume were added to aqueous solutions of phosphoric acid and drops of the resulting compositions were applied to plates stained in accordance with the procedure previously outlined, except that the test plates were baked for three hours instead of two hours. The concentration of the ingredients of each solution and the average stain removal rate for each composition are set forth in Table V below. This example illustrates stain removal compositions which can be prepared in stainless steel Table II Calculated FeCl 38.0 6.3 25.4 12.7 0.6 6.3 12.7 25.4 6.3 0.6

Dest-Jniuig time, Sec- 90 155 35 10 45 20 10 l 15 EXAMPLE HI equipment without corroding that equipment. The ex- Ferrous chloride was added to aqueous solutions of phosphoric acid and the resulting compositions were applied to test plates stained in accordance with the pro cedure previously described and the rates of stain removal were measured. The concentration of phosphoric acid and ferrous chloride in each solution and stain removal rates are set forth in Table III below. It will be noted from the table that an aqueous solution of 10 weight percent phosphoric acid to which has been added 25.4 weight percent ferrous chloride (40 weight percent FeCl -4H O) is about as effective as a 20 percent solution of hydrochloric acid. This example is significant because it demonstrates that a mild acid, in this instance phosphoric acid, to which has been added ferrous chlo ride, is as effective as the more concentrated and hazardtent of the corrosion of these compositions was determined by immersing a 316 stainless steel panel in the stain removal solution for four hours at 95 F. The surfactant employed was a liquid nonionic dispersant marketed by the Antara Division of the General Aniline and Film Corporation under the trade designation Igepal CO-630. In addition to the nonionic surfactants, anionic type surfactants can also be employed with the compositions of the invention. The alkylarylsulfonates are illustrative of the anionic surfactants which can be used. Since the latter type surfactants tend to be incompatible with the acid system, a coupling agent such as isopropanol is employed to prevent phase separation of the anionic surfactant from the acidulous portion of the composition.

EXAMPLE VI This example illustrates a preferred bowl cleaning composition particularly adaptcd for sale in the industrial and domestic market. In this composition, the acid and soluble ferrous salts are formulated with an anionic surfactant, a non-ionic surfactant and perfume. The concentration of the components of this composition are set forth in Table VI.

Table VI H PO (75%) 23.90 FeCl (34.5%) 10.40 FeSO -7H O 13.10 Nonionic surfactant 1 0.35

Perfume 0.05

Isopropanol 10.00 Anionic surfactant 2 0.50 H O 41.70

1 Nonyl plionoxy polyoxyothylene ethanol wherein the molecule contains, by weight. 65% polyoxyethylene and is prepared by condensing 9-10 mols of ethylene oxide with 1 mol of nonyl phenol.

-Alk vl benzene sodium sultonate wherein the alkyl group contains from 10-15 carbon atoms.

In addition to having highly effective stain removal properties, this composition also has germicidal properties. Thus, this composition was tested using the AOAC Method against M.p.v. aureus at C. In th1s test the endpoint for phenol was at a dilution of 1 to 60, which is the most acceptable figure for this organism. The composition had a phenol coeflicient of 2.11.

EXAMPLE VII Ferrous chloride is added to an aqueous solution of hydrochloric acid and phosphoric acid and drops of the resulting compositions are applied to plates stained in accordance with the procedure previously outlined. The concentration of the ingredients of each solution and the stain removal rates are set forth in Table VII below.

Table VII Dcstaining time, See 20 1-5 minutes. The acid detergent composition is then withdrawn and the area is rinsed with water. When more persistent stains are encountered, it will be necessary, of course, to contact the stains with the acidic compositions of the invention for a longer period of time. The exact time will be readily apparent, however, to those having ordinary skill in this art.

This application is a continuation-in-part of our copending application Serial No. 731,192, filed April 28, 1958, now abandoned.

It will be understood that various changes, modifications and alterations may be made in the instant invention without departing from the spirit and scope thereof and as such the invention is not to be limited except by the appended claims.

We claim:

1. An aqueous acid detergent solution of at least about 0.2 weight percent of an acid selected from the group consisting of phosphoric acid. hydrochloric acid and mixtures thereof and at least about 0.5 weight percent of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof.

2. The acid detergent solution of claim 1 wherein the acid is phosphoric acid.

3. The acid detergent solution of claim 1 wherein the acid is hydrochloric acid.

4. The acid detergent solution of claim 1 wherein the ferrous salt is ferrous chloride.

5. An aqueous acid detergent solution of about 0.2 to 30 weight percent of an acid selected from the group consisting of phosphoric acid, hydrochloric acid and mixtures thereof and about 0.5 to 38 Weight percent of a watersoluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof.

6. An acid detergent solution in accordance with claim 5 wherein said acid is a mixture of hydrochloric and phosphoric acids and up to about weight percent of said acid is phosphoric acid.

7. An aqueous acid detergent solution of about 5 to 25 weight percent of phosphoric acid and about 6 to 30 weight percent of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof.

8. An aqueous acid detergent solution of about 6 to 20 weight percent of hydrochloric acid and about 1 to 24 weight percent of a water-soluble ferrous salt selected from the group consistingof ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof.

9. An aqueous acid detergent solution of about 18 to 22 weight percent of phosphoric acid, about 2 to 6 weight percent of ferrous chloride and about 6 to 10 weight percent of ferrous sulfate.

10. An aqueous acid detergent solution of about 5 to 25 weight percent of phosphoric acid, about 6 to 30 weight percent of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof, about 10 weight percent of isopropanol and about 0.5 weight percent of an alkyl benzene sodium sulfonate wherein the alkyl group contains from about 10 to 15 carbon atoms.

11. A process for removing iron stains from porcelaintype fixtures which comprises contacting said stains with an aqueous acid detergent solution, withdrawing said detergent solution and rinsing with water, said detergent solution comprising at least about 0.2% of an acid selected from the group consisting of phosphoric acid, hydrochloric acid and mixtures thereof and at least about 0.5 weight percent of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof.

12. A process for removing iron stains from porcelaintype fixtures which comprises contacting said stains with an aqueous acid detergent solution, withdrawing said detergent solution and rinsing with water, said detergent solution comprising about 0.2 to 30 Weight percent of an acid selected from the group consisting of phosphoric acid, hydrochloric acid and mixtures thereof and 0.5 to 38 weight percent of a water-soluble ferrous salt selected from the group consisting of ferrous chloride, ferrous sulfate, ferrous nitrate and mixtures thereof.

References Cited in the file of this patent UNITED STATES PATENTS 10 Phair Nov. 4, 1924 McGaughey May 3, 1938 Halpern Nov. 14, 1950 Chester et al. Oct. 2, 1951 McDonald et al. Apr. 6, 1954 FOREIGN PATENTS Australia Nov. 16, 1955 OTHER REFERENCES Uses and Applications of Chemicals and Related Materials" by Gregory, Reinhold Publ. Co. (1939), p. 288. 

5. AN AQUEOUS ACID DETERGENT SOLUTION OF ABOUT 0.2 TO 30 WEIGHT PERCENT OF AN ACID SELECTED FROM THE GROUP CONSISTING OF PHOSPHORIC ACID, HYDROCHLORIC ACID AND MIXTURES THEREOF AND ABOUT 0.5 TO 38 WEIGHT PERCENT OF A WATERSOLUBLE FEROUS SALT SELECTED FROM THE GROUP CONSISTING OF FERROUS CHLORIDE, FERROUS SULFATE, FERROUS NITRATE AND MIXTURES THEREOF. 